铸造Al-Si合金熔体处理——晶粒细化

Melt treatment for AlSi Casting AlloysGrain Refining

对亚共晶Ａｌ－Ｓｉ铸造合金进行细化处理已成为一种基本操作。中间合金（Ａｌ－Ｔｉ，Ａｌ－Ｔｉ－Ｂ和Ａｌ－Ｂ合金）在亚共晶Ａｌ－Ｓｉ铸造合金中与在工业纯铝和变形铝合金中的晶粒细化行为存在较大的差异。Ａｌ－３Ｔｉ－３Ｂ，Ａｌ－３Ｂ中间合金在Ａｌ－Ｓｉ铸造合金中表现出优异的晶粒细化效应，Ｓｉ与晶粒细化剂的交互作用在其中扮演着重要的角色。通过炉前对熔体进行快速热分析可以对晶粒细化效果和变质程度进行评价和预测，继而控制熔体处理的质量。对于亚共晶Ａｌ－Ｓｉ铸造合金，归纳起来有四种晶粒细化机理：包晶反应理论、共晶反应理论、硼化物颗粒理论和超形核理论。仅对Ａｌ－Ｓｉ铸造合金细化处理的最新进展。

Grain refining in hypoeutectic AlSi casting alloys has become an essential practice of melt treatment. The grain refinement with three types of master alloys: binary AlTi, binary AlB, and ternary AlTiB with Ti or B in excess of the TiB2 stoichiometry, in hypoeutectic AlSi casting alloys was different from that in commercial purity aluminum and its wrought aluminum alloys. Al3Ti3B and Al3B master alloys exhibited very excellent grain refining ability in hypoeutectic AlSi casting alloys and the interaction between Si and grain refiners was thought to play an important role during grain refinement. The quality of melt treatment in AlSi alloy could be controlled by evaluating and predicting the grain refinement and modification with differential thermal analysis equipment. There are four grain refinement mechanisms in hypoeutectic AlSi casting alloys: peritectic reaction theory, eutectic reaction theory, boride particles theory, and hypernucleation theory. The recent development of grain refining, intera